DESCRIPTION: (Applicant's Description) Natural killer (NK) cells have been shown to be important in defense against tumors and infections. The overall goal of this application is to study in vivo NK cell trafficking to anatomical sites to deliver functions. Experiments will be carried out using responses characterized during murine cytomegalovirus (MCMV) infections of mice. NK cells and cytokines are induced following MCMV infection and function to mediate protection in liver. NK cells form inflammatory foci associated with sites of MCMV antigen expression and IFN-Y production at these sites. In contrast, monocyte/macrophage localize in both inflammatory foci and disperse in sinusoidal cavities. The NK cell inflammation and delivery of antiviral defenses is dependent on the chemokine macrophage inflammatory protein I-alpha (MIP-1-alpha). MIP-1-alpha gene expression and protein production are elevated at coinciding times, and mice deficient in MIP-1-alpha function are dramatically inhibited in both inflammatory and protective liver responses. The experiments presented here will continue characterization of NK cell trafficking and will define the cellular and cytosine-mediated mechanisms of inflammation and virus control in vivo. The main hypotheses are: 1) MCMV infection induces the release of cytokines (e.g. IL-12 or EL-15) and/or chemokines from macrophage, Kupffer cells, and/or hepatocytes, which 2) amplify MIP-l-alpha production from other uninfected cells, 3) to mediate MIP-I-alpha adhesion of NK cells to ICAM-1 on vascular endothelium or endothelial cells of liver, 4) promoting NK cell trafficking and production of MIP-l-alpha from inflammatory cells, and 5) facilitating NK cell delivery of IFN-gamma at sites of MCMV infection to induce macrophage activation. These will be examined by asking the following questions in four Specific Aims. 1) What signals are initiating induction of chemokines in liver, and what role do cytokines play in induction of chemokines? 2) Which cell types are stimulated to produce MIP-l-alpha? 3) Are other steps promoting MIP-l-alpha dependent NK cell trafficking? 4) Is NK cell trafficking to other compartments dependent on different mechanisms? Molecular, histological, immunological, and cell trafficking studies will be used to answer these questions. The experiments will take advantage of mice genetically deficient in cytokines, cytosine receptors, and MIP-1-alpha, as well as mice characterized as NK- and T cell-deficient. Information resulting from these studies will yield significant and novel information for developing anti-viral and anticancer treatment protocols.